The development of effective prophylactic and therapeutic medicaments for preventing and inhibiting the cytotoxic potential of infections of enveloped viruses, and in particular of Herpes Simplex Viruses (HSV's) and Human Immunodeficiency Viruses (HIV's), have proven difficult.
Herpes Simplex Viruses (such as HSV-1 and HSV-2) are widespread. Prophylactic and therapeutic medicaments and methods developed for the prevention and treatment of infections of herpes simplex viruses have, in general, only been partially successful.
Secretions of human milk have long been known to exhibit antiviral activity see Matthews et al., Lancet, 2: 1388-1390 (1976); Micheals, R. H., J. Immunol., 94: 262-271 (1964); Laegried et al., Acta Paedriatz Scand., 75: 696-701 (1986); and Isaacs et al., J. Infect. Dis., 154: 060-971 (1986)!. In particular, whole human breast milk has "in vitro" been noted to exhibit antiviral neutralizing activity against herpes simplex virus 2. Lopez et al., Arch. Fr. Pediatr., 46: 263-265 (1989)!. While the origins of this antiviral activity has been attributed to several varying sources, it has never been able to be definitively characterized.
The primary source of the antiviral activity of milk has been attributed to the presence of immunoglobins (IgG's) therein. Other sources that have been suggested as the origin of this antiviral activity includes a non-lipid macromolecule that is relatively stable to heat (Matthews et al., and Micheals, both supra) and/or a molecule having a molecular weight of 400,000 daltons (laegried et al., supra) and/or a component of the lipid layer that effects only encapsulated viruses (issacs et al., supra). This inability to definitely characterize the antiviral origin(s) of milk limits the use thereof, or of components or systems thereof, for antiviral purposes.
Human saliva has also long been known to be active against a number of viruses, including herpes simplex virus 1. see Gyselink, et al., J. Infect. Dis., 137: 583-586 (1978)!. Unfortunately, the origin of the anti-viral activity of human saliva has not been definitively characterized, being ascribed variously to glycoproteins Learner, et al., J. Immunol. 96: 59-63 (1966)!, immunoglobulin A Tomasi, J. clin. Invest. 42: 1552-1560 (1963)! or immunoglobulin G (Gyselink, et al., supra). More recently, it has further been suggested that the antiviral activity may be more of a cell-protective activity than a virus neutralizing activity--that is to say, the saliva directly affects the oral epithelial cells, protecting them against infection see Heineman, H. S., and M. S. Greenberg, Archs Oral Biol. 225: 257-261 (1980)!. Unfortunately, the origin of such activity still remains unknown.
No medicament has been successful in preventing and inhibiting infections of, and the cytotoxic potential of, herpes simplex viruses in all stages.
The human immunodeficiency viruses (HIV's) are fatal and widespread and have only relatively recently been identified. The biochemistry and physiology of these HIV's are poorly known and understood. It has been reported that "in vitro" contact, for at least one-half hour or more, with whole human saliva inhibits the ability of human immunodeficiency virus (HIV) to infect phytohaemagglutinin-stimulated lymphocytes. Fultz, Lancet, 2:1215 (1986)!. However, shorter periods of incubation have failed to demonstrate an impressive antiseptic effect (see Fultz, supra). Moreover, not all of the saliva samples reported can insure a 100% inhibition of HIV-1 infectivity see Fox et al., JADA, 118: 709-711 (1989)!.
As yet, no medicaments or methods of which we are aware have proven to be consistently successful for preventing and treating infections of, and the cytotoxic potential, of the HIV's.
Other enveloped viruses that are particularly troublesome to effectively prevent and treat include herpes viruses (such as Varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human herpes virus-6), the paramyxoviruses (such as human parainfluenza viruses), the family of orthomyxoviruses (such as the influenza type viruses A and B), rotaviruses, coronaviruses and retroviruses (such as Human T-cell leukemia virus-1, bovine leukemia virus and simian immunodeficiency virus).
It is well known that natural antimicrobial agents are contained in most natural external mammalian secretions. In particular, the naturally-occurring antimicrobial thiocyanate/peroxidase/H.sub.2 O.sub.2 systems present in saliva and in milk have been extensively studied.
In saliva, an antimicrobial peroxidase-dependent system has been described which can generate hypothiocyanite (OSCN-), as follows: ##STR1## Oram and Reiter, Biochem. J., 100:373-381 (1966); Hogg and Jago, Biochem. J., 117: 779-790 (1970); and Carlsson et al., Infect. Immun., 44: 581-586 (1984)!. The peroxidases thought to be present in saliva that oxidize thiocyanate in this system include salivary peroxidase and lactoperoxidase. A similar antimicrobial lactoperoxidase-dependent system has also been identified in milk. Oram and Reiter, Biochem. J., 100:382 (1966)!. Indeed, it has been suggested that the same peroxidase/thiocyanate/hydrogen peroxide system that operates in saliva also operates in milk. see Klebanoff, S. J., et al., J. Dent Res. (supp.) p.86 (1965).!
The antimicrobial efficiency of the thiocyanate/peroxidase/hydrogen peroxide system has been demonstrated "in vitro" against several bacteria known to be responsible for frequent destruction of teeth and/or periodontium See Carlsson, supra, and Courtois et al., J. Dent. Res. 68 (spec. issue):1002 (1989)!. The antimicrobial efficiency of this system was also demonstrated "in vivo" in cases of aphtous lesions of the buccal mucosa Hoogendoorn and Piessens. J. Oral Pathol., 16: 425-427 (1987)!.
Unfortunately, the precise antimicrobal mechanism of the thiocyanate/peroxidase/H.sub.2 O.sub.2 system has not been definitely characterized. However, it is believed that at physiological pH, hypothiocyanite (generated by this system) mediates the oxidation of essential proteins and enzymes sulfhydryls groups of the bacteria, resulting in microbial inhibition. Additionally, it has been suggested that lactoperoxidase may be responsible for the formation of higher oxyacids of the thiocyanate ion, such as cyanosulfurous and cyanosulfuric acids, which may also be responsible for antimicrobial inhibition. Bjoerck, L., and O. Claesson, J. Dairy Sci. 63:919-921 (1980); Hogg, et al., supra; and Pruitt, et al., Biochemistry 21:562-567 (1982)!.
Antimicrobial dentifrices that contain a thiocyanate/peroxidase/hydrogen peroxide system are known. Upon oral administration, the enzyme-dependent systems in these antimicrobial dentifrices are activated by various components (such as oxygen and/or water) of the natural chemical environment of the oral cavity. In particular, U.S. Pat. No. 4,564,519 issued to Pellico et al., (hereinafter sometimes referred to as Pellico '519) discloses a di-enzymatic chewable orally-activated antimicrobial dentifrice that includes a thiocyanate salt and lactoperoxidase which, through interaction with hydrogen peroxide formed by another enzymatic system in the dentifrice, produces a bacterial inhibitor in the form of a negative, monovalent hypothiocyanite ion (OSCN--) which exists in solution in acid-base equilibrium with hypothiocyanous acid (HOSCN).
Also, in U.S. Pat. No. 4,576,817 issued to Montgomery et al., it was disclosed to provide antimicrobial enzymatic bandages and pads for disinfection purposes. These pads include a serum-activated oxidoreductase enzyme for producing hydrogen peroxide upon contact of the enzymatic materials with serum. In one embodiment, these antimicrobial bandages are formulated to also include a peroxidatic peroxidase, such as lactoperoxidase.
In the journal BIOFUTUR (February, 1990, at page 52), a system is disclosed having two enzymes that, in tandem, generates toxic radicals that may be useful for the treatment of various infections. This system includes glucose oxidase which, in the presence of glucose, generates H.sub.2 O.sub.2. This system also includes a peroxidase which, with the H.sub.2 O.sub.2, generates iodides that are highly toxic for the cell. Unfortunately, the precise mechanism of this toxicity is not known. It was further reported therein that this glucose oxidase/peroxidase system has been coupled to a monoclonal antibody against Candida albicans and has been found effective for protecting against such infections in mice. This glucose oxidase/peroxidase system has also been coupled to a monoclonal antibody for the epitope of the gp 120 fraction of HIV and has been found to be effective against infections of Sacharomyces expressing this epitope.
In the journal CLINICAL RESEARCH, vol. 36, No. 5 (1988) at 809A, a lactoperoxidase-halide-hydrogen peroxide (LHHP) system was reported to be effective, in vitro, on respiratory syncytial virus (RSV) replication. It was also suggested that a myeloperoxidase-halide-peroxidase system (that plays an important role in host defense mechanisms against phagocytosed bacteria) may also have a role in host defense against RSV.
Finally, in PCT patent application, no. WO 8912457, the incorporation of myeloperoxidase with a carrier is disclosed for administration to humans for reinforcing the natural antibody activity thereof at the macrophage level. In this disclosure, purified myeloperoxidase is linked with a carrier that has an affinity for the macrophage, so that the carrier will transport the myeloperoxidase to where it may be captured and utilized by the macrophage for antibody defense. Carriers disclosed include antibodies, or fragments thereof that have an affinity for the macrophages. Other suggested carriers include particular liposomes and human serum albumin. Preferably, the myeloperoxidase and the linked carrier are formed utilizing recombinant DNA technologies. Such a composition is provided to aid, augment and reinforce the bodies natural antibody defenses and is believed to be useful in combatting various infections, including HIV.
Despite the long-standing coexistence of the knowledge of the properties of the peroxidases and the thiocyanate/peroxidase/hydrogen peroxide system, as well as the need for prophylatic and therapeutic medicaments for the prevention and treatment of infections of enveloped viruses (and in particular of herpes simplex and human immunodeficiency viruses), to the best of our knowledge no one has utilized medicaments incorporating such peroxidases or peroxide systems for the prevention or treatment of infections of enveloped viruses and, in particular, for the prevention and treatment of herpes simplex and human immunodeficiency virus infections.
Thus, it can be seen that there remains a need for prophylactic and therapeutic peroxidase medicaments which prevent and/or treat infections of enveloped viruses, including HSV and HIV, and for prophylactic and therapeutic applications of peroxidases in a medicament that may be administered to an individual in need thereof without depending upon naturally-occurring concentrations of substrate, oxygen donors or peroxidases for their inhibitory effect. Finally, there remains a need for methods for the prevention and treatment of infections of enveloped viruses, including HSV's and HIV's, by the administration of prophylactic and therapeutically effective amounts of such peroxidase medicaments to an individual in need thereof.